Ceramic filters are well known in the art and at least one is described in U.S. Pat. No. 4,431,977 for a "Ceramic Bandpass Filter". Prior art ceramic bandpass filters are at least partially constructed from blocks of ceramic material, are relatively large and are typically coupled to other electronic circuitry through discrete wires, cables, and pins attached or coupled to connection points on external surfaces of the blocks.
It is also well known that some major objectives in electronic designs are reduced physical size, increased reliability, improved manufacturability and reduced manufacturing cost. To achieve these somewhat conflicting objectives, electronic circuits are increasingly being manufactured using so-called surface-mount techniques. Surface-mount is a manufacturing technique by which electronic components are attached to a circuitry substrate or circuit board without using metallic leads that extend from a package or electronic component. Small connection nodes on typically only one side of a greatly reduced size package, are electrically joined to corresponding connection nodes on a substrate or circuit board by either a wave soldering or reflow soldering technique. The registration, or alignment, of the connection nodes on the component with the connection nodes on the circuit board or substrate must be carefully maintained during assembly. Eliminating connection leads on electronic components and using surface mount techniques permits great reductions in the physical size of an electronic circuit and a significant increase in its reliability by reducing a significant source of electrical failures.
A prior art surface mount ceramic filter is shown in U.S. Pat. No. 5,146,193 to Sokola. While the surface mount ceramic filter shown in this patent addresses the short comings of its prior art, the filter shown in this patent as well as other ceramic filter patents might benefit from still other improvements. Such other improvements would include improved isolation of the input/output pads from each other and the ability to adjust or control the location of transmission zeroes. A block filter that improves I/O isolation, overall frequency response, and permits adjustment of transmission zeroes would be an improvement over the prior art.